Scholarly Works, Fish and Wildlife Conservation

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Characterization of Antibiotic Resistance in Escherichia coli from Meat Products and Human Samples in Botswana Using Molecular and Whole-Genome Approaches
Yi, Saehah; Bywater, Auja; Dintwe, Galaletsang; Sies, Ashton; Haidl, Thomas; Cameron, Andrew; Alexander, Kathleen A.; Ponder, Monica A. (2025-07-30)
Introduction: Botswana experiences high diarrheal illness rates in rural areas like the Chobe region, where E. coli from meat products and food handlers may contribute to antibiotic resistance (ABR) transmission, posing a potential threat to public health. Purpose: Characterize the ABR profiles of E. coli isolated from meat products and human feces to explore potential links between meat and human ABR transmission. Methods: Meat (chicken and beef) were collected from local grocery stores, and human fecal samples were obtained from food handlers in Kasane, Botswana. E. coli isolates were obtained by selective enrichment and plating on EMB and MacConkey agars. ABR profiles were determined for 12 antibiotics using the CLSI disk diffusion method. Whole-genome sequencing was performed on multidrug-resistant isolates using the Illumina Miseq platform and genomes were analyzed using Galaxy and BV-BRC. Results: E. coli was isolated from 66 of 124 meat samples and 230 of 507 human fecal samples, with 56.06% (37/66) of meat isolates and 43.04% (99/230) of human isolates showing resistance to at least one antibiotic. Multidrug resistance (MDR) was detected in 30.30% (20/66) of meat isolates and 11.74% (27/230) of human isolates. Disk diffusion testing revealed that tetracycline and trimethoprim/sulfamethoxazole were the most frequently detected resistances across both meat and human isolates. Whole-genome sequencing identified no shared sequence types (STs) between E. coli isolates from meat and human samples. However, both sources carried the same ABR genes, including sul2, blaTEM-1, tetA, and qnrS1, along with shared plasmid types (IncFIB, IncFII, IncX1), while integrons, detected only in meat isolates, suggest horizontal gene transfer through mobile genetic elements. Significance: The detection of shared antibiotic resistance genes and plasmid types between meat and human isolates underscores the importance of monitoring meat products to inform strategies for mitigating the transmission of antibiotic resistance in Botswana.
Water as a Driver of Antibiotic-Resistant and Pathogenic Escherichia coli Transmission in Areas with Mixed Land Use
Yi, Saehah; Alexander, Kathleen A.; Sies, Ashton; Cameron, Andrew; Cheng, Rachel; Ponder, Monica A. (2025-10-24)
Introduction: Aquatic environments are critical reservoirs and transmission pathways for Escherichia coli, linking human populations with surrounding ecosystems. The Chobe River in northern Botswana is a vital water source for people, livestock, and wildlife, creating opportunities for microbial exchange at the human-environment interface. Areas upstream of Kasane are protected parkland with limited human inputs. We hypothesized that anthropogenic drivers increase the persistence of antibiotic resistance (ABR) and pathogenic E. coli and that environmental isolates will be more similar to human isolates. Methods: Water (n = 324) was collected along a transect passing through pristine, mixed-land use and town environments. Human fecal samples (n = 507) were collected in Kasane, Botswana. E. coli isolates were obtained by selective enrichment and plating on EMB, passed for purity on MacConkey agar, and confirmed through phoA gene amplification by PCR. ABR profiles were determined against 12 antibiotics using CLSI disk diffusion. Whole-genome sequencing (WGS) was performed on 12 multidrug-resistant isolates (six per source) on Illumina NextSeq platform, and genomes were analyzed in Galaxy and the BV-BRC platform. Results: E. coli was recovered from 96.60% (313/324) of water samples and 45.4% (230/507) of human fecal samples. Resistance to at least one antibiotic was detected in 27.16% (85/313) of water isolates and 43.0% (99/230) of human isolates, and multidrug resistance was observed in 12.78% (40/313) and 11.7% (27/230) of isolates, respectively. By land-use, ABR prevalence among water isolates was 33.33% (25/75) in mixed-use areas, 34.31% (35/102) in town areas, and 18.38% (25/136) in park areas. ABR patterns were similar across sources, with ampicillin, tetracycline, streptomycin, and trimethoprim/sulfamethoxazole being the most common. WGS revealed distinct sequence type (ST) distributions, with water isolates dominated by ST11 whereas human isolates spanned six different STs. Although no STs were shared between sources, one water isolate (ST2852) collected near town clustered with human isolates in the phylogeny. Human genomes carried multiple acquired ABR genes including blaCTX-M-15, blaTEM-1, qnrS1, tetA/B, and sul2, whereas water genomes lacked frequently acquired resistance genes despite exhibiting multidrug-resistant phenotypes. Virulence profiling identified shared adhesins and secretion systems across sources, while water isolates carried LEE, stx1, and hemolysin genes, and human isolates encoded siderophore systems, toxins, and serum resistance factors. All isolates from water and human were predicted to be human pathogens with probability > 0.9. Significance: This study highlights the circulation of antibiotic-resistant and potentially pathogenic E. coli across water and human sources in the Chobe region. Differences across land-use contexts indicate an anthropogenic signal shaping resistance ecology along the river. The detection of multidrug-resistant phenotypes in both sources, distinct sequence type distributions, and phylogenetic proximity of a town-adjacent water isolate to human genomes underscores the importance of genomic surveillance at the human-environment interface. Water serves as a major driver of E. coli transmission, facilitating the spread of ABR and pathogenic strains between humans and the environment. These findings provide a framework for monitoring resistance emergence in shared water systems, including the Chobe River, and for guiding strategies to mitigate public health risks.
The Many Hosts of Mycobacteria 9 (MHM9): A conference report
Klever, Abigail Marie; Alexander, Kathleen A.; Almeida, Deepak; Anderson, Matthew Z.; Ball, Ray L.; Beamer, Gillian; Boggiatto, Paola; Buikstra, Jane E.; Chandler, Bruce; Claeys, Tiffany A.; Concha, Aislinn E.; Converse, Paul J.; Derbyshire, Keith M.; Dobos, Karen M.; Dupnik, Kathryn M.; Endsley, Janice J.; Endsley, Mark A.; Fennelly, Kevin; Franco-Paredes, Carlos; Hagge, Deanna A.; Hall-Stoodley, Luanne; Hayes Jr., Don; Hirschfeld, Katherine; Hofman, Courtney A.; Honda, Jennifer R.; Hull, Natalie M.; Kramnik, Igor; Lacourciere, Karen; Lahiri, Ramanuj; Lamont, Elise A.; Larsen, Michelle H.; Lemaire, Timothy; Lesellier, Sandrine; Lee, Naomi R.; Lowry, Christopher A.; Mahfooz, Najmus S.; McMichael, Temet M.; Merling, Marlena R.; Miller, Michele A.; Nagajyothi, Jyothi F.; Nelson, Elizabeth; Nuermberger, Eric L.; Pena, Maria T.; Perea, Claudia; Podell, Brendan K.; Pyle, Charlie J.; Quinn, Fred D.; Rajarama, Murugesan V. S.; Mejiaa, Oscar Rosas; Rothoffk, Michelle; Sagol, Saydie A.; Salvador, Liliana C. M.; Simonsonao, Andrew W.; Spencer, John S.; Sreevatsan, Srinand; Subbian, Selvakumar; Sunstrum, James; Tobin, David M.; Vijayan, K. K. Vidya; Wright, Caelan T. O.; Robinson, Richard T. (Elsevier, 2023-09)
The Many Hosts of Mycobacteria (MHM) meeting series brings together basic scientists, clinicians and veterinarians to promote robust discussion and dissemination of recent advances in our knowledge of numerous mycobacterial diseases, including human and bovine tuberculosis (TB), nontuberculous mycobacteria (NTM) infection, Hansen's disease (leprosy), Buruli ulcer and Johne's disease. The 9th MHM conference (MHM9) was held in July 2022 at The Ohio State University (OSU) and centered around the theme of “Confounders of Mycobacterial Disease.” Confounders can and often do drive the transmission of mycobacterial diseases, as well as impact surveillance and treatment outcomes. Various confounders were presented and discussed at MHM9 including those that originate from the host (comorbidities and coinfections) as well as those arising from the environment (e.g., zoonotic exposures), economic inequality (e.g. healthcare disparities), stigma (a confounder of leprosy and TB for millennia), and historical neglect (a confounder in Native American Nations). This conference report summarizes select talks given at MHM9 highlighting recent research advances, as well as talks regarding the historic and ongoing impact of TB and other infectious diseases on Native American Nations, including those in Southwestern Alaska where the regional TB incidence rate is among the highest in the Western hemisphere.
Size-dependence of food intake and mortality interact with temperature and seasonality to drive diversity in fish life histories
Kindsvater, Holly K.; Juan-Jorda, Maria-Jose; Dulvy, Nicholas K.; Horswill, Cat; Matthiopoulos, Jason; Mangel, Marc (Wiley, 2024-02)
Understanding how growth and reproduction will adapt to changing environmental conditions is a fundamental question in evolutionary ecology, but predicting the responses of specific taxa is challenging. Analyses of the physiological effects of climate change upon life history evolution rarely consider alternative hypothesized mechanisms, such as size-dependent foraging and the risk of predation, simultaneously shaping optimal growth patterns. To test for interactions between these mechanisms, we embedded a state-dependent energetic model in an ecosystem size-spectrum to ask whether prey availability (foraging) and risk of predation experienced by individual fish can explain observed diversity in life histories of fishes. We found that asymptotic growth emerged from size-based foraging and reproductive and mortality patterns in the context of ecosystem food web interactions. While more productive ecosystems led to larger body sizes, the effects of temperature on metabolic costs had only small effects on size. To validate our model, we ran it for abiotic scenarios corresponding to the ecological lifestyles of three tuna species, considering environments that included seasonal variation in temperature. We successfully predicted realistic patterns of growth, reproduction, and mortality of all three tuna species. We found that individuals grew larger when environmental conditions varied seasonally, and spawning was restricted to part of the year (corresponding to their migration from temperate to tropical waters). Growing larger was advantageous because foraging and spawning opportunities were seasonally constrained. This mechanism could explain the evolution of gigantism in temperate tunas. Our approach addresses variation in food availability and individual risk as well as metabolic processes and offers a promising approach to understand fish life-history responses to changing ocean conditions.
Stopover Hotspots for Migratory Birds in North and Central America
Feng, Shi; Yang, Qinmin; Qiao, Huijie; Escobar, Luis E.; Yan, Xuan (University of Kansas Libraries, 2025-05)
Despite the large body of literature on avian migratory behavior, there is little information about stopover sites during bird movement, including the population-level drivers of breeding grounds and wintering grounds. Stopovers play an essential role in bird migratory site chains for energy supply and rest. There is an urgent need to identify and protect stopover sites to secure the long-term sustainability of migratory network connectivity and stability. To address this challenge, we reconstructed a migration network and identified geographic hotspots denoted as stopover sites. And we analyzed the high-density population movements of 52 focal migratory bird species using comprehensive observation data from eBird through PageRank algorithm. Furthermore, potential alternative stopover sites were explored using a word embedding technique based on geo-functional similarity. Our study was conducted in North and Central America during a three-year period and revealed three key stopover areas, including Florida peninsula and its inland, the region of Central America, and the region near Puget Sound. Results from this study can be used for conservation prioritization guidance, active surveillance of bird pathogens, and bird management.
Factors affecting the growth of a moss species necessary for nesting habitat restoration of the four-toed salamander (Hemidactylium scutatum, Temminck and Schlegel 1838)
Hilt, Miriam E.; Brooks, George C.; Hamed, M. Kevin; Faison, Emory L. (Amphibian Conservation Research Center & Lab, 2025-11)
Habitat loss and degradation is threatening amphibian populations worldwide. The four-toed salamander, Hemidactylium scutatum, is a small plethodontid salamander that deposits eggs terrestrially in moss clumps overhanging vernal pools. Hemidactylium scutatum has declined across its range, largely due to the loss of wetland habitat necessary for breeding. Constructed ponds and wetlands are common tools used to combat amphibian declines, but they often require several years for natural vegetation communities to establish. As a result, there have been calls to better understand the factors that promote the growth of critical habitat components to refine ex situ cultivation methods and expedite restoration effort. Here we evaluate the factors that influence the growth of Climacium americanum moss, a preferred nesting substrate of H. scutatum, in a greenhouse setting. We examined the impacts of plant density, soil type, and soil moisture on changes in biomass. Our analysis determined that density has little impact on growth rates while two of the three soil types had a significantly higher change in mass. We determined soil moisture–as a result of soil type–is the most critical component in greenhouse-grown moss, with plants in the 75^th quartile of moisture seeing the largest positive change in biomass. Our results show that growing moss in greenhouses for use in constructed wetlands is achievable when proper soil moisture is maintained. Ultimately, this work aids restoration efforts for H. scutatum by providing a simple methodology to produce high volumes of nesting habitat and promote population recovery.
Association Between Reduced Upstream Riparian Forest Cover and Impaired Development of Embryos From Eastern Hellbenders (Cryptobranchus alleganiensis)
Funkhouser, Holly A.; Case, Brian F.; Groffen, Jordy; Holloway, Austin; Hopkins, William A. (Wiley, 2025-01)
Populations of the Eastern Hellbender, (a large-bodied, fully aquatic salamander) inhabiting stream reaches with low catchment-wide riparian forest cover upstream, have experienced population declines and a shift toward a geriatric population age structure. These population declines and demographic shifts might be attributed to reduced embryo viability. Reduced egg quality/viability could negatively affect recruitment and has also been known to trigger filial cannibalism in other species. Therefore, we hypothesized that in comparison to high forest cover sites, hellbender eggs collected from low forest cover sites would have a greater incidence of developmental abnormalities and lower overall viability, and that this would predict whole-clutch cannibalism by the attending male. We collected a subset of eggs (~20–35) from 99 clutches across sites with variable upstream riparian forest cover and reared these eggs through hatching in stream water under controlled laboratory conditions. At the same time, we monitored the fate of the remaining eggs from the same clutches in the field to document the frequency of whole-clutch filial cannibalism. We found that eggs collected from sites with lower upstream forest cover had significantly shorter embryonic development times and produced a lower percentage of viable hatchlings (hatchlings with normal development times and morphology). The average modelled viability of hatchlings was 70% higher in sites with the highest forest cover compared to our sites with the lowest forest cover. In contrast to our predictions, we did not find evidence to suggest that egg viability in the lab predicted whole-clutch cannibalism in the field. Although forest cover was a significant predictor of egg viability and underdevelopment, substantial variance in embryonic developmental traits was unaccounted for in our models suggesting that traits associated with adults (e.g., egg and/or sperm quality) may also play a role in determining developmental outcomes. Further experiments are needed to identify what factors (e.g., egg quality, water quality) disrupt the embryonic development of hellbenders as well as the proximate stimulus that causes adult male hellbenders to eat their young. Our results emphasise the importance of restoring and protecting riparian forest cover to conserve sensitive stream species.
Modulation of Paternal Care Behaviors in Response to Stream Conditions by Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis)
O'Brien, Rebecca S. M.; Groffen, Jordy; Dayer, Ashley A.; Hopkins, William A. (Oxford University Press, 2025-03-20)
The rapid environmental changes associated with the Anthropocene mean that flexible behavioral responses may be a critical determinant of animals’ resiliency to anthropogenic disturbance, particularly for species with long generation times and low vagility. One type of behavior that exemplifies this potentially important flexibility is parental care. Eggs and juvenile animals are sensitive to environmental stressors, and the ability of parents to adjust care behaviors to buffer their offspring from rapidly changing conditions may be critical to successful reproduction. In this study, we explore the role of parental care in buffering eggs from anthropogenic stressors in the long-lived, fully aquatic eastern hellbender salamander (Cryptobranchus alleganiensis alleganiensis). Using custom-designed infrared cameras installed in underwater artificial shelters in a natural stream, we describe hellbender paternal care behaviors in greater detail than has previously been possible, assess the extent to which hellbender fathers buffer their eggs from increasing levels of silt and decreasing concentrations of dissolved oxygen in nesting cavities, and describe the possible trade-offs that hellbender fathers exhibit between paternal care and self-maintenance behaviors. We found that while hellbender parents buffered their offspring from low dissolved oxygen concentrations by increasing parental care, there was an apparent trade-off between parental care and self-maintenance responses to low oxygen. Hellbender fathers did not show evidence of buffering their offspring from the effects of increasing silt or organic material in their nest cavities. We also found that filial cannibalism is a widespread behavior across nests, with almost all fathers exhibiting some cannibalism, although the extent varied widely. Our study indicates that hellbender parents may be able to reduce the impacts of declines in dissolved oxygen concentration on their offspring to a limited extent, but they may be unable to fully protect offspring from increasing silt.
Parasite Infections Influence Immunological Responses But Not Reproductive Success of Male Hellbender Salamanders (Cryptobranchus alleganiensis)
Slack, Katherine Louise; Groffen, Jordy; Davis, A. K.; Hopkins, William A. (Oxford University Press, 2025-04-03)
The emergence and spread of infectious diseases is a significant contributor to global amphibian declines, requiring increased surveillance and research. We assessed host–vector–parasite dynamics using a population of eastern hellbender salamanders (Cryptobranchus alleganiensis) that harbor leeches (Placobdella appalachiensis) that transmit endoparasitic blood parasites(Trypanosoma spp) to the host, with coinfection frequently occurring. We centered our study on adult males throughout their extended 8-month paternal care period because recent research indicates that nest failure caused by lack of paternal care and filial cannibalism is contributing to hellbender population declines. Recognizing the potential for parasites to modulate host physiology and behavior, we explored how infection severity influences paternal health and reproductive success. We assessed white blood cell profiles of adult male hellbenders in response to parasites, coinfection, and seasonal temperature fluctuations, while also investigating whether parasite infection or coinfection was predictive of nest success. We found that hellbenders exhibited seasonal shifts in white blood cell indices; as temperatures increased across seasons (from 5°C to 20°C), the proportion of neutrophils and eosinophils decreased (by 14% and 46%, respectively) in circulation while the proportion of lymphocytes and basophils increased (by 8% and 101%, respectively). Moreover, the proportion of neutrophil precursors increased by 80% under colder temperatures, which signifies seasonal immune cell recruitment. We demonstrated that neutrophils and eosinophils increased while lymphocytes decreased in response to leech infection. However, as leech and trypanosome infection intensity increased together, the proportion of lymphocytes increased while neutrophils and eosinophils decreased, underscoring the complex interactions between coinfection and immune responses of hellbenders that warrant future research. Despite the influence of infection and coinfection on hellbender physiology, we detected no evidence to support the hypothesis that parasites influence the likelihood of nest failure or whole-clutch filial cannibalism. In light of amphibian declines being exacerbated by climate change and disease, our study emphasizes the need to establish hematological reference values that account for physiological adaptations to seasonal fluctuations in temperature and different life history stages and to study the physiological responses of imperiled amphibian species to parasites.
Some of these are not like the others: Relative thermal sensitivity among anuran species of the Southeast United States
DuBose, Traci P.; Moore, Chloe E.; Farallo, Vincent R.; Benson, Abigail L.; Hopkins, William A.; Silknetter, Sam; Mims, Meryl C. (Wiley, 2025-08-14)
Estimating how close a species is to its upper thermal limits (i.e., warming tolerance, a thermal sensitivity index) and how that proximity changes across space enables spatially explicit identification of species with increased extinction risk as temperatures increase. Yet, thermal sensitivity is often difficult to calculate because it is the result of many traits. We aimed to synthesize multiple traits into a single estimate of relative terrestrial thermal sensitivity for 13 anuran species in the southeastern United States. We employed models that incorporate traits and microclimate variation to (1) estimate species warming tolerance (the difference between species critical thermal maximum and modeled operative temperature, an estimate of body temperature) and (2) investigate how warming tolerance varied with latitude (whereby latitude represents different temperature regimes and external drivers of thermal sensitivity). We ran mechanistic niche models across a 12° latitudinal gradient and 10 years to estimate individual operative temperature. We calculated the minimum, 25th percentile (hottest quarter), and median daily minimum warming tolerance. Estimates of minimum warming tolerance spanned −5 to 10°C (Lithobates palustris and Gastrophryne carolinensis respectively) and differed among species. For most species, modeled operative temperatures exceeded species' critical thermal maximum during extreme warm temperatures (i.e., heat waves) in part of their range, and warming tolerance increased with latitude. During heat waves, five species had lower warming tolerance at higher latitudes, and three species' warming tolerance did not change with latitude. We identified species that are approaching their thermal limits in the Southeast and characterized spatial patterns of warming tolerance. Increased temperatures could increase anuran extinction risk, posing an additional challenge for threatened anuran species. Spatial patterns of warming tolerance were not consistent among species in our study, highlighting that patterns identified at higher taxonomic categories could be inconsistent at lower taxonomic categories.
Climate change adaptation and adaptive efficacy in the inland fisheries of the Lake Victoria basin
Nyboer, Elizabeth A.; Musinguzi, Laban; Ogutu-Ohwayo, Richard; Natugonza, Vianny; Cooke, Steven J.; Young, Nathan; Chapman, Lauren J. (Wiley, 2022-10)
Inland fisheries support the livelihoods of millions of people in riparian communities worldwide but are influenced by increasing climate variability and change. Freshwater fishing societies are among the most vulnerable to climate change given their dependence on highly threatened aquatic resources. As climate change intensifies, building adaptive capacity within communities and understanding the efficacy of adaptive strategies for maintaining household stability is essential for coping with ongoing social and environmental change. In this study, we examined household perceptions of climate change, livelihood impacts and responses to socio-ecological changes in fishing-dependent households in the Lake Victoria basin in Uganda, East Africa. Through a series of household surveys and focus group discussions in five fish landing sites, we assessed social adaptive capacity (SAC) based on 207 households and identified adaptive strategies that are effective for coping with climatic change. We found that people in fishing households are aware of environmental change but that most households do not have adaptive strategies that are efficacious for securing long-term income and food security. We also investigated household demographics that contribute to SAC, examined links between SAC and adaptive efficacy and established potential routes towards developing effective adaptive approaches in small-scale fisheries. This work contributes to a growing foundation of documented community-based knowledge for building adaptive capacity in inland fisheries and the communities around the world that depend on them. Read the free Plain Language Summary for this article on the Journal blog.
Overturning stereotypes: The fuzzy boundary between recreational and subsistence inland fisheries
Nyboer, Elizabeth A.; Embke, Holly S.; Robertson, Ashley M.; Arlinghaus, Robert; Bower, Shannon; Baigun, Claudio; Beard, Douglas; Cooke, Steven J.; Cowx, Ian G.; Koehn, John D.; Lyach, Roman; Milardi, Marco; Potts, Warren; Lynch, Abigail J. (Wiley, 2022-11)
Inland recreational fisheries provide numerous socio-economic benefits to fishers, families and communities. Recreationally harvested fish are also frequently consumed and may provide affordable and sustainable but undervalued contributions to human nutrition. Quantifying the degree to which recreationally harvested fish contribute to food security and subsistence is impeded by lack of data on harvest and consumption and by the difficulty in differentiating among recreational and subsistence fisheries. Recreational harvest records tend to be limited to wealthy, food-secure countries and well-monitored fisheries with clear regulations or permitting systems. These records often neglect components of recreational harvest among food-insecure fishers who are potentially more likely to have consumption as a motivation. Here, we highlight the ‘fuzzy boundary’ that can exist between inland recreational and subsistence fisheries and argue that unreported consumption is likely to be a hidden contributor to food security in some populations. We draw on local case studies from around the world to highlight specific instances where recreationally harvested fish species contribute food and subsistence benefits to participating communities. We use these examples to highlight the diversity of ways that inland recreational fisheries contribute to human nutrition, knowledge gaps in understanding recreational fishing for food, and consequences of not accounting for them as food fisheries in policy and management. The aim of this paper is to draw the attention of resource managers and policy makers, create greater social awareness of the importance of recreational fisheries and bring to light this hidden contribution of inland fisheries to nutrition and subsistence.
Towards vibrant fish populations and sustainable fisheries that benefit all: learning from the last 30 years to inform the next 30 years
Cooke, Steven J.; Fulton, Elizabeth A.; Sauer, Warwick H. H.; Lynch, Abigail J.; Link, Jason S.; Koning, Aaron A.; Jena, Joykrushna; Silva, Luiz G. M.; King, Alison J.; Kelly, Rachel; Osborne, Matthew; Nakamura, Julia; Preece, Ann L.; Hagiwara, Atsushi; Forsberg, Kerstin; Kellner, Julie B.; Coscia, Ilaria; Helyar, Sarah; Barange, Manuel; Nyboer, Elizabeth A.; Williams, Meryl J.; Chuenpagdee, Ratana; Begg, Gavin A.; Gillanders, Bronwyn M. (Springer, 2023-06)
A common goal among fisheries science professionals, stakeholders, and rights holders is to ensure the persistence and resilience of vibrant fish populations and sustainable, equitable fisheries in diverse aquatic ecosystems, from small headwater streams to offshore pelagic waters. Achieving this goal requires a complex intersection of science and management, and a recognition of the interconnections among people, place, and fish that govern these tightly coupled socioecological and sociotechnical systems. The World Fisheries Congress (WFC) convenes every four years and provides a unique global forum to debate and discuss threats, issues, and opportunities facing fish populations and fisheries. The 2021 WFC meeting, hosted remotely in Adelaide, Australia, marked the 30th year since the first meeting was held in Athens, Greece, and provided an opportunity to reflect on progress made in the past 30 years and provide guidance for the future. We assembled a diverse team of individuals involved with the Adelaide WFC and reflected on the major challenges that faced fish and fisheries over the past 30 years, discussed progress toward overcoming those challenges, and then used themes that emerged during the Congress to identify issues and opportunities to improve sustainability in the world's fisheries for the next 30 years. Key future needs and opportunities identified include: rethinking fisheries management systems and modelling approaches, modernizing and integrating assessment and information systems, being responsive and flexible in addressing persistent and emerging threats to fish and fisheries, mainstreaming the human dimension of fisheries, rethinking governance, policy and compliance, and achieving equity and inclusion in fisheries. We also identified a number of cross-cutting themes including better understanding the role of fish as nutrition in a hungry world, adapting to climate change, embracing transdisciplinarity, respecting Indigenous knowledge systems, thinking ahead with foresight science, and working together across scales. By reflecting on the past and thinking about the future, we aim to provide guidance for achieving our mutual goal of sustaining vibrant fish populations and sustainable fisheries that benefit all. We hope that this prospective thinking can serve as a guide to (i) assess progress towards achieving this lofty goal and (ii) refine our path with input from new and emerging voices and approaches in fisheries science, management, and stewardship.
On embracing the concept of becoming environmental problem solvers: the trainee perspective on key elements of success, essential skills, and mindset
Gale, A. P.; Chapman, J. O.; White, D. E.; Ahluwalia, P.; Williamson, A. K. J.; Peacock, K. R.; Akagbosu, R.; Lepine, T. M.; Arizor, I.; Bone, L. A.; Brown, J.; Fahrngruber, A. M.; Goldberg-Flood, A.; Kovirineni, S.; Lamb-Laurin, S. J.; Zia, N.; Innocent, S.; Lee, W.; Moran, G.; Nwasoria, B.; Ouellette, N. A.; Pendlebury, R.; Prue, A.; Sokolowski, J.; Namutosi, P.; Tesfay, T.; Oliver, M. C. M.; Nyboer, Elizabeth A.; Cooke, S. J. (Canadian Science Publishing, 2022-01-01)
Life in the Anthropocene is characterized by many environmental problems, and unfortunately, more continue to emerge. Although much effort is focused on identifying problems, this does not necessarily translate to solutions. This situation extends to the training environment, where students are often adept at understanding and dissecting problems but are rarely explicitly equipped with the skills and mindset to solve them. Herein, a group of undergraduate students and their instructors consider the concept of becoming environmental problem solvers. We first identified themes associated with historical and contemporary environmental successes that emerged from our reading, or more specifically, we identify the elements that underlie environmental success stories. The key elements of success involved setting clear objectives, identifying the scale of the problem, learning from failure, and consulting diverse knowledge sources. Next, we reflected on the skills and mindset that would best serve environmental problem solvers and enable future successes. Essential skills include innovative and critical thinking, ability to engage in collaborative teamwork, capacity to work across boundaries, and resilience. In terms of mindset, key attributes include the need for courage, enthusiasm and commitment, optimism, open mindedness, tenacity, and adaptability. We conclude with a brief discussion of ideas for revising training and curriculum to ensure that students are equipped with the aforementioned skills and mindset. The ideas shared here should contribute to ensuring that the next generation of learners have the ability to develop solutions that will work for the benefit of the environment, biodiversity, and humanity. Solving environmental problems will increasingly fall to the next generation, so it is time to ensure that they are prepared for that task.
Global recreational consumption of non-native inland fish: higher economic benefits, but lower nutritional value and climate resilience
Milardi, Marco; Wood, Louisa E.; Nyboer, Elizabeth A.; Embke, Holly S.; Phang, Sui C.; Lynch, Abigail J. (Elsevier, 2025-11-20)
Inland recreational fisheries are globally significant leisure pursuits, with well-documented benefits to human health and well-being, but also one of the principal drivers of non-native fish introductions to enhance fishing opportunities, whether for sport or sustenance. In this study, we assess the relative reliance of global inland recreational fisheries on non-native versus native species for harvest. We further examine how this reliance varies by economic and nutritional value as well as the climate vulnerability of the species involved. We demonstrate that, of the 1,325,851 t of inland recreational fishes recreationally harvested for consumption worldwide in 2021, non-native fish were a small proportion (4 %; 53,651 t). On a global scale, non-native fish contributed a net positive 38.2 % economic value to inland recreational harvest. However, they also contributed a net negative −21.9 % nutritional value to inland recreational harvest. Non-native fishes were also more climate vulnerable (i.e., higher average climate vulnerability index values) and thus proportionally increased overall estimates of climate vulnerability with a net positive of 70.9 %. Our results quantitatively demonstrate that non-native species play a more important role in inland consumptive recreational fisheries than their mere harvest volume would suggest. However, many nuances were seen on the continent and country scale, which reflect the complexity of fisher behavior, fish distribution and socio-economic factors. Our findings help unravel the complex effects of non-native species on human activities and underscore the need to evaluate their global impacts holistically.
Managing exploitation of freshwater species and aggregates to protect and restore freshwater biodiversity
Cooke, Steven J.; Piczak, Morgan L.; Nyboer, Elizabeth A.; Michalski, Fernanda; Bennett, Abigail; Koning, Aaron A.; Hughes, Kathy A.; Chen, Yushun; Wu, Jinming; Cowx, Ian G.; Koehnken, Lois; Raghavan, Rajeev; Pompeu, Paulo S.; Phang, Sui; Valbo-Jorgensen, John; Bendixen, Mette; Torres, Aurora; Getahun, Abebe; Kondolf, G. Mathias; Acreman, Michael C.; Song, Andrew M.; Taylor, William W. (Canadian Science Publishing, 2024-09)
For millennia humans have extracted biological and physical resources from the planet to sustain societies and enable the development of technology and infrastructure. Growth in the human population and changing consumption patterns have increased the human footprint on ecosystems and their biodiversity, including in fresh waters. Freshwater ecosystems and biodiversity face many threats and it is now widely accepted that we are in a biodiversity crisis. One means of protecting and restoring freshwater biodiversity is to better manage the exploitation of freshwater biota and aggregate resources (e.g., sand, gravel, and boulders). Here we outline the threats arising from such exploitation and identify response options to ensure that methods and levels of extraction are sustainable and allow recovery of over-exploited freshwater biodiversity and ecosystems. The guidance we provide will enable practitioners, policy-makers, and resource stewards to embrace effective, sustainable, and evidence-based approaches to resource extraction. Response options for managing species exploitation include strengthening assessment and reporting, using science-based approaches to reduce overexploitation and support recovery, embracing community engagement, and building or tightening legislation. Response options for managing exploitation of freshwater aggregate resources include reducing demand for harvest, strengthening governance, reporting, and monitoring of environmental impacts, and promoting the restoration of degraded ecosystems or compensating for losses. Diverse case studies highlight examples of where various management actions have been implemented in an effort to consider how they can be scaled up and adapted to other contexts. Managing exploitation will be a key aspect of broader initiatives needed to protect and restore freshwater biodiversity around the globe.
Sexual and spatio-temporal variation of Lake Erie Walleye growth and maturity: A consequence of multiple impacting factors
Ma, Qiuyun; Jiao, Yan; Zhou, Can; Ren, Yiping (Elsevier, 2021-07-01)
Sexual and spatio-temporal variations have been observed in the life history parameters of many aquatic species and their causes have been related to harvesting pressure and environmental changes. This study aims to explore sexual, spatial and temporal variation in the growth and maturity through weight-at-length, length-at-age, and maturity-at-length relationships for Lake Erie Walleye (Sander vitreus) as a case to test some hypotheses. Hypotheses on whether harvest pressure and environmental changes (both local and global scale) caused the temporal changes of these life history traits were further diagnosed. Sexual and spatio-temporal variations in these life history traits were formulated using mixed-effects models. Our study found that geographic basin, sex, year and cohort all have substantial effects on the growth and maturity of Walleye based on survey data from 1989 to 2015. Multiple factors including water supply of Lake Erie, temperature, fishing pressure of Walleye, and global climate factors were found to correlate with the temporal variations of growth and maturity of Walleye significantly. Our findings should contribute to the future interpretation of Walleye life history variations and population dynamics. The methodology constructed in this study could be applied to explore the heterogeneity and impacting factors for other species in aquatic ecosystems.
Predatory impacts of invasive Blue Catfish in an Atlantic coast estuary
Hilling, Corbin D.; Schmitt, Joseph D.; Jiao, Yan; Orth, Donald J. (Wiley, 2023-10)
Objective: Predatory invasive fishes may consume species of management interest and alter food webs. Blue Catfish Ictalurus furcatus is a large-bodied, salinity-tolerant species that exhibits broad diet breadth and preys on species of both conservation concern and fisheries management interest. To better understand the ecological consequences of the establishment of Blue Catfish fisheries, estimates of predatory impacts are needed. Methods: Using a Monte Carlo simulation, we integrated abundance estimates, diet information, and consumption-to-biomass ratios to estimate population-level Blue Catfish predation for a large Chesapeake Bay tributary along the mid-Atlantic coast of the United States, the James River. Result: Population-level annual predation estimates by Blue Catfish exceeded 100 metric tons for several species or taxa of interest, including an estimated 400.7 metric tons (95% CI = 272.6–613.2) of blue crab Callinectes sapidus. Prey species abundances were unknown and thus limited opportunities to evaluate prey population responses. For instance, effects of Blue Catfish on blue crab populations remain unknown without tributary-specific estimates of blue crab abundance, but comparisons to landings data suggests that Blue Catfish predation on blue crab in the James River may be low compared with harvest. Conclusion: Estimation of Blue Catfish predatory effects may inform development of management goals and objectives that balance diverse stakeholder interests. This work provides beneficial information to assess trade-offs of Blue Catfish fisheries and their effects on coastal aquatic resources.
Management strategy evaluation to assess trade-offs associated with invasive Blue Catfish fisheries and predation impacts
Hilling, Corbin D.; Jiao, Yan; Schmitt, Joseph D.; Fabrizio, Mary C.; Angermeier, Paul L.; Orth, Donald J. (Oxford University Press, 2025-04)
Objective: Many species are intentionally introduced beyond their native range to provide benefits to humans (e.g., food, recreation, or biocontrol). However, introduced species can become invasive and can harm native species, prompting resource managers to explore options to simultaneously conserve native biota and enhance fishing opportunities. Management of Chesapeake Bay Blue Catfish Ictalurus furcatus is complicated because the species supports a renowned trophy fishery and commercial and recreational harvest but also negatively affects native species. Consequently, there is uncertainty and disagreement on how to balance trade-offs associated with varying stakeholder interests. Methods: We used a management strategy evaluation to project Blue Catfish population dynamics into the future under different fishery policies to understand whether fishery yield, trophy fishing opportunities, and predation on the economically and ecologically important blue crab Callinectes sapidus could be optimized in the James River, a Chesapeake Bay subestuary. Results: Simulated population trajectories indicated that objectives related to maintaining fisheries and conserving prey populations were in conflict. Policies that increased the yield and abundance of trophy-size Blue Catfish (≥100 cm total length) generally increased predation on the blue crab, which supports a valuable fishery. Intense harvest of smaller length-classes and protection of larger Blue Catfish yielded outcomes in which trophy fish abundance increased and blue crab predation declined compared to baseline conditions. However, these outcomes were generally associated with lower Blue Catfish yields after 25 years. There were zero scenarios in which the fishery yield increased and blue crab predation decreased after 25 years. Policies limiting the harvest of small Blue Catfish resulted in large population abundances, suggesting that reducing the abundance of small fish could be important for reducing impacts on native species. Conclusions: This study supports the importance of management planning to develop objectives and performance measures based on an improved understanding of trade-offs associated with harvest management for a nonnative fish with economic value.
Recovery of Delaware Bay horseshoe crabs following harvest reductions
Sweka, John A.; Anstead, Kristen A.; Smith, David R.; Barry, Linda; Zimmerman, Jordan; Doctor, Steve; Weedon, Craig; Gartland, James; Jiao, Yan; Ferretti, Francesco; Hallerman, Eric M. (Oxford University Press, 2025-09)
Objective: Horseshoe crabs Limulus polyphemus play a vital role in the Delaware Bay ecosystem. The migratory stopover of several shorebird species occurs during the horseshoe crab spawning season, and the eggs of horseshoe crabs provide an essential food source to fuel their northward migration to breeding areas. High commercial fishery use of horseshoe crabs as bait during the 1990s coincided with a decline in crabs and shorebirds, particularly the red knot Calidris canutus rufa, which has been listed as threatened under the U.S. Endangered Species Act since 2015. In response to the population decline of shorebirds, the Atlantic States Marine Fisheries Commission began reducing the harvest of horseshoe crabs in 2000 with a goal of rebuilding the population of horseshoe crabs and shorebirds that depend upon them. The objective of this analysis was to determine whether horseshoe crab harvest management in the Delaware Bay region has increased the abundance of the species in recent years. Methods: We analyzed data from fisheries-independent trawl surveys of horseshoe crab relative abundance using a Bayesian hierarchical model to determine whether harvest management has resulted in the rebuilding of the horseshoe crab population to levels seen in 1990—a period before the overuse of horseshoe crabs and the decline in the population of red knots. Results: Data from multiple surveys showed that the horseshoe crab population in Delaware Bay declined from the 1990s through approximately 2005, was relatively low and stable until 2010, and then increased through 2023, with a 0.38 probability of exceeding the 1990 level. Conclusions: The results of this analysis support the effectiveness of management decisions related to horseshoe crabs in the Delaware Bay region. In response to harvest restrictions, the abundance of horseshoe crabs has neared levels observed in the early 1990s—a period prior to high commercial use and a decline in both horseshoe crabs and shorebirds that depend on them for food during annual migrations.

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